Walter s



(No Model.)

W. S. BISHOP. SAFETY FUSE FOR ELECTRIC GONDUGTORS.

No. 409,628. Patented Aug. 20 1889.

ATTORNEYS.

UNITED STATES PATENT OFFICE.

\VALTER S. BISHOP, OF NEXV HAVEN, CONNECTICUT, ASSIGNOR TO HIMSELF AND FRANK B. PARDEE, OF SAME PLACE.

SAFETY-FUSE FOR ELECTRIC CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 409,628, dated August 20, 1889.

Application filed November 23, 1888. Serial No. 291,624. (No model.)

To all whom it may concern:

Be it known that I, WALTER S. Brsnor, of New Haven, in the county of New Haven and State of Connecticut, have invented a new and Improved Safety-Fuse for Electric Conductors, of which the following is a specification, reference being had to the annexed drawings, forming a part thereof, in which- Figure 1 is a perspective view of my improved safety-fuse for electric conductors. Fig. 2 is a plan view of the fusible metal strip. Fig. 3 is a plan view of the fusible metal strip with its protecting mica plate, I 5 and Fig. at is a vertical transverse section through one of the binding-posts.

Similar letters of reference indicate corresponding parts in all the views.

The object of my invention is to provide a simple and eflicient safety-fuse for telegraph and telephone circuits for preventing in ury to the instruments and apparatus when a current above the normal working"- current passes over the line-as, for example, when the line-wires are crossed with electriclight wires, or when the line is struck by lightning.

My invention consists in the combination, with suitable supports, of a thin strip of 0 fusible metal placed between the supports and protected by a plate of insulating material, such as mica.

It also further consists in the combination, with the protected fusible strip, of an incom- 55 bustible non-condueting plate arranged between the fusible strip and the base-piece of the safety-fuse.

In the safety-fuse which I have shown in the drawings I have represented two pairs 4,0 of binding-posts-one for the line and the other for the local circuit. As these safetyfuses are alike a description of one will answer for both.

To the base-piece A are attached the bind- 5 ing-posts B 3 by means of screws a. Each binding-post is formed of a nut 1) bearing upon the base-piece A, a washer a, and a cap-piece c, apertured and tapped to receive the screws (1 and provided with a shoulder d, also apertured transversely to receive the conductor, and provided at the top with a screw 6 for binding the conductor in the post. The washer a, and nut h are apertured to receive the pin h, which is drawn through the said nut and washer to keep them from turning.

Between the base A and the nut 12 is placed a plate f, of incombustible material, which is also a non-conductor of electricity, such as mica. The said plate f extends from the post B to the post B. Between the shoulders d of the binding-posts and the nuts 1) are clamped the apertured ends g of the fusiblennetal strip 0, the said strip being reduced in width between the apertured ends to increase its resistance and facilitate its melting when a heavy current passes from one binding-post to the other. The strip 0 is protected by a plate D, of mica or analogous material, which fits around the shouldered at opposite ends, and is of sufficient width to prevent injury to the fusible strip 0.

In some instances, as in the case of a telephone-line, where only a high-tension current is employed, the strip 0 may have a very high 7 5 resistance. It may be made of thin tin or lead-foil and cemented to the mica plate D. \Nhen a current greater than the normal current of a telegraph or telephone line passes over the line, upon reaching the fusi- 8o ble strip O the said strip is melted and the circuit is broken. The strip 0 is readily replaced after removing the upper ends of the binding-posts.

In carrying out my invention I do not limit myself to the exact form and proportions illustrated and described, as these may be varied to suit the taste of different manufacturers and to adapt the fuse to different uses.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. In a safety-fuse for electric circuits, the combination, with the binding-posts B B, 95 formed of the part c b, and screw a, of the fusible strip C, provided with the apertured ends g and the protectingplate D, the said fusible strip and protecting-plate being arproteeting-piavteD, and the plate f, substanranged to be clamped by the binding-posts, tially as specified. substantially as specified.

2. In a safety-fuse for electric circuits, the WAL FER BISHOP '5 combination, with the binding-posts B B, Vitnesses:

provided with the shoulders (1,0f the strip ELBRIDGE F. BARNES, 0, havingthe apertured ends g, the mica M. S. TADHAM. 

